m-trieu commented on code in PR #34053: URL: https://github.com/apache/beam/pull/34053#discussion_r2026157313
########## runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/streaming/harness/BackendWorkerMetadataVendor.java: ########## @@ -0,0 +1,181 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +package org.apache.beam.runners.dataflow.worker.streaming.harness; + +import static org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions.checkState; + +import java.util.concurrent.CompletableFuture; +import java.util.concurrent.CountDownLatch; +import java.util.concurrent.ExecutorService; +import java.util.concurrent.Executors; +import java.util.concurrent.TimeUnit; +import java.util.function.Consumer; +import javax.annotation.concurrent.ThreadSafe; +import org.apache.beam.runners.dataflow.worker.windmill.Windmill.WorkerMetadataResponse; +import org.apache.beam.runners.dataflow.worker.windmill.WindmillEndpoints; +import org.apache.beam.runners.dataflow.worker.windmill.client.WindmillStream.GetWorkerMetadataStream; +import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.util.concurrent.ThreadFactoryBuilder; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * Manages vending the backend worker metadata to a single consumer. + * + * <p>Internally restarts the underlying {@link GetWorkerMetadataStream} to gracefully close the + * stream and prevent gRPC {@link + * org.apache.beam.vendor.grpc.v1p69p0.io.grpc.Status#DEADLINE_EXCEEDED} statuses. + */ +@ThreadSafe +final class BackendWorkerMetadataVendor { + private static final Logger LOG = LoggerFactory.getLogger(BackendWorkerMetadataVendor.class); + private static final int GET_WORKER_METADATA_STREAM_TIMEOUT_MINUTES = 3; + private static final String BACKEND_WORKER_METADATA_VENDOR_THREAD_NAME = + "BackendWorkerMetadataVendorThread-%d"; + private static final WorkerMetadataResponse NO_WORKER_METADATA = + WorkerMetadataResponse.getDefaultInstance(); + + private final WorkerMetadataStreamFactory getWorkerMetadataStreamFactory; + private final ExecutorService fetchBackendWorkerMetadataExecutor; + private final CountDownLatch initialStreamStarted; + + // Writes are synchronized on "this", reads are lock-free. + private volatile boolean isStarted; + // Writes are synchronized on "this", reads are lock-free. + private volatile boolean isShutdown; + + private BackendWorkerMetadataVendor( + WorkerMetadataStreamFactory getWorkerMetadataStreamFactory, + ExecutorService fetchBackendWorkerMetadataExecutor) { + this.getWorkerMetadataStreamFactory = getWorkerMetadataStreamFactory; + this.fetchBackendWorkerMetadataExecutor = fetchBackendWorkerMetadataExecutor; + this.initialStreamStarted = new CountDownLatch(1); + } + + static BackendWorkerMetadataVendor create( + WorkerMetadataStreamFactory getWorkerMetadataStreamFactory) { + return new BackendWorkerMetadataVendor( + getWorkerMetadataStreamFactory, + Executors.newSingleThreadExecutor( + new ThreadFactoryBuilder() + .setNameFormat(BACKEND_WORKER_METADATA_VENDOR_THREAD_NAME) + .build())); + } + + /** + * Starts the vending of backend worker metadata, passing it to endpointsConsumer for processing. + * Returns a {@link CompletableFuture} that can be used to block until the initial {@link + * GetWorkerMetadataStream} has been started. + */ + synchronized void start(Consumer<WindmillEndpoints> endpointsConsumer) { + checkState(!isStarted, "Multiple calls to BackendWorkerMetadataVendor.start() is not allowed."); + checkState(!isShutdown, "BackendWorkerMetadataVendor has previously been shutdown."); + LOG.debug("Starting WorkerMetadataVendor..."); + + fetchBackendWorkerMetadataExecutor.execute( + () -> { + WorkerMetadataResponse initialWorkerMetadata = NO_WORKER_METADATA; + + while (true) { + GetWorkerMetadataStream getWorkerMetadataStream = + getWorkerMetadataStreamFactory.create(initialWorkerMetadata, endpointsConsumer); + LOG.debug( + "Starting GetWorkerMetadataStream w/ metadata version {}.", + initialWorkerMetadata.getMetadataVersion()); + getWorkerMetadataStream.start(); + initialStreamStarted.countDown(); + + // Await stream termination and propagate the most current worker metadata to start + // the next stream. + try { + initialWorkerMetadata = awaitGracefulTermination(getWorkerMetadataStream); + } catch (InterruptedException e) { + if (isShutdown) { + break; + } + + throw new IllegalStateException( Review Comment: done -- This is an automated message from the Apache Git Service. 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